This paper describes the dispersion encoded sparse signal reconstruction algorithm based on k-domain extraction to suppress the complex conjugate mirror term in frequency domain Optical Coherence Tomography (OCT). This algorithm uses the numerical dispersion compensation to acquire the unmatched dispersion phase, meanwhile adopts the sparse signal reconstruction algorithm to extract the frequency spectrum of the peak and its corresponding mirror iteratively. This algorithm reduces the numbers of the FFT per iteration and cancels the complex conjugate mirror term. The experiment result demonstrated that the algorithm can suppress the complex conjugates effectively, and computational velocity improves 46.1%.